1. Field of the Invention
The present invention relates to a substrate processing apparatus for performing a series of treatments on various types of substrates such as a semiconductor wafer and a glass substrate for a liquid crystal display device. In particular, the present invention relates to an improved substrate processing apparatus which comprises both a thermal processing part and a non-thermal processing part.
2. Description of the Background Art
As well known in the art, a semiconductor wafer undergoes various surface treatments such as coating of a resist liquid and relevant treatments. To automatically perform a series of surface treatments, an automatic semiconductor processing apparatus is used. A number of techniques have been developed to efficiently perform those surface treatments. For instance, a technique disclosed by Japanese Patent Laid-Open Gazette No. 2-132840 arranges a plurality of processing parts in two rows and transports a semiconductor wafer among the processing parts by means of a single transport robot.
In many cases, those treatments include a thermal treatment such as baking. Meanwhile, treatments such as resist coating and resist developing of a semiconductor wafer are usually performed at a normal temperature (room temperature). These non-thermal treatments are performed at a very strictly controlled temperature so that the temperature of the semiconductor wafer and the temperatures at the processing parts are maintained at predetermined temperatures close to a normal temperature.
Despite this requirement, the conventional technique referred to above uses only one transport robot to access both thermal processing parts and non-thermal processing parts. After heated at the thermal processing parts, the transport robot inserts its hand into the non-thermal processing parts. Even though a semiconductor wafer needs be still maintained at a normal temperature, the transport robot holds the semiconductor wafer with its warmed hand. Heat radiated from a warmed semiconductor wafer locally increases temperatures of other semiconductor wafers and the non-thermal processing parts. These all result instable thermal treatments.
Further, since only one transport robot accesses all processing parts, the overall through put of the apparatus is low.
Still further, every time the transport robot inserts its hand in and out of the thermal processing parts, heated air and particles scatter from the thermal processing parts and flow into the non-thermal processing parts, thereby the deteriorating thermal stability at the non-thermal processing parts and polluting the non-thermal processing parts.